package main

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"ucl.lmika.dev/ucl"
	"ucl.lmika.dev/ucl/builtins"
)

func newTestPlugins() (*PluginFilters, *ucl.Inst) {
	plugins := newPluginFilters()
	inst := ucl.New(
		ucl.WithModule(plugins.Module()),
		ucl.WithModule(builtins.Strs()),
	)
	return plugins, inst
}

func writePluginFile(t *testing.T, dir, name, content string) {
	t.Helper()
	path := filepath.Join(dir, name)
	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		t.Fatal(err)
	}
}

func TestPluginFilters_LoadDir(t *testing.T) {
	ctx := context.Background()

	t.Run("registers filter from upper-case example", func(t *testing.T) {
		plugins, inst := newTestPlugins()
		dir := t.TempDir()
		writePluginFile(t, dir, "upper.ucl", `
d:filter "String: To Upper Case" { |in|
  strs:to-upper $in
}
`)

		plugins.LoadDir(ctx, inst, dir)

		if len(plugins.Errors()) != 0 {
			t.Fatalf("unexpected errors: %v", plugins.Errors())
		}
		proc, ok := plugins.filters["plugin:string-to-upper-case"]
		if !ok {
			t.Fatalf("filter not registered, have %v", plugins.filters)
		}
		if proc.Label != "String: To Upper Case" {
			t.Errorf("label = %q", proc.Label)
		}
		res, err := proc.Filter(ctx, "abc")
		if err != nil {
			t.Fatal(err)
		}
		if res.Output != "ABC" || res.Append {
			t.Errorf("got %+v", res)
		}
	})

	t.Run("finds nested files and ignores non-ucl files", func(t *testing.T) {
		plugins, inst := newTestPlugins()
		dir := t.TempDir()
		writePluginFile(t, dir, "sub/dir/nested.ucl", `d:filter "Nested" { |in| $in }`)
		writePluginFile(t, dir, "notes.txt", `d:filter "Ignored" { |in| $in }`)
		writePluginFile(t, dir, "README.md", `this is not ucl {`)

		plugins.LoadDir(ctx, inst, dir)

		if len(plugins.Errors()) != 0 {
			t.Fatalf("unexpected errors: %v", plugins.Errors())
		}
		if _, ok := plugins.filters["plugin:nested"]; !ok {
			t.Error("nested filter not registered")
		}
		if _, ok := plugins.filters["plugin:ignored"]; ok {
			t.Error("non-ucl file should have been ignored")
		}
	})

	t.Run("missing directory is not an error", func(t *testing.T) {
		plugins, inst := newTestPlugins()

		plugins.LoadDir(ctx, inst, filepath.Join(t.TempDir(), "does-not-exist"))

		if len(plugins.Errors()) != 0 {
			t.Fatalf("unexpected errors: %v", plugins.Errors())
		}
		if len(plugins.filters) != 0 {
			t.Errorf("unexpected filters: %v", plugins.filters)
		}
	})

	t.Run("bad file is reported and sibling still loads", func(t *testing.T) {
		plugins, inst := newTestPlugins()
		dir := t.TempDir()
		writePluginFile(t, dir, "a-bad.ucl", `d:filter "Broken" { |in| `)
		writePluginFile(t, dir, "b-good.ucl", `d:filter "Good" { |in| $in }`)
		writePluginFile(t, dir, "c-bad-usage.ucl", `d:filter "Only Label"`)

		plugins.LoadDir(ctx, inst, dir)

		errs := plugins.Errors()
		if len(errs) != 2 {
			t.Fatalf("expected 2 errors, got %v", errs)
		}
		if !strings.Contains(errs[0].Error(), "a-bad.ucl") {
			t.Errorf("first error should name the file: %v", errs[0])
		}
		if !strings.Contains(errs[1].Error(), "c-bad-usage.ucl") {
			t.Errorf("second error should name the file: %v", errs[1])
		}
		if _, ok := plugins.filters["plugin:good"]; !ok {
			t.Error("good filter not registered")
		}
		if _, ok := plugins.filters["plugin:broken"]; ok {
			t.Error("broken filter should not be registered")
		}
	})

	t.Run("later definition with same label wins", func(t *testing.T) {
		plugins, inst := newTestPlugins()
		dir := t.TempDir()
		writePluginFile(t, dir, "01-first.ucl", `d:filter "Dup" { |in| "first" }`)
		writePluginFile(t, dir, "02-second.ucl", `d:filter "Dup" { |in| "second" }`)

		plugins.LoadDir(ctx, inst, dir)

		if len(plugins.filters) != 1 {
			t.Fatalf("expected 1 filter, got %v", plugins.filters)
		}
		res, err := plugins.filters["plugin:dup"].Filter(ctx, "x")
		if err != nil {
			t.Fatal(err)
		}
		if res.Output != "second" {
			t.Errorf("output = %q", res.Output)
		}
	})

	t.Run("procs defined in plugin files are reusable", func(t *testing.T) {
		plugins, inst := newTestPlugins()
		dir := t.TempDir()
		writePluginFile(t, dir, "helpers.ucl", `
proc shout { |s| strs:to-upper $s }
d:filter "Shout" { |in| shout $in }
`)

		plugins.LoadDir(ctx, inst, dir)

		if len(plugins.Errors()) != 0 {
			t.Fatalf("unexpected errors: %v", plugins.Errors())
		}
		res, err := plugins.filters["plugin:shout"].Filter(ctx, "hi")
		if err != nil {
			t.Fatal(err)
		}
		if res.Output != "HI" {
			t.Errorf("output = %q", res.Output)
		}
	})
}

func TestPluginFilters_ProcResults(t *testing.T) {
	ctx := context.Background()

	tests := []struct {
		name    string
		script  string
		input   string
		want    string
		wantErr string
	}{
		{
			name:   "string result used as-is",
			script: `d:filter "F" { |in| strs:to-upper $in }`,
			input:  "abc",
			want:   "ABC",
		},
		{
			name:   "non-string result is stringified",
			script: `d:filter "F" { |in| add 40 2 }`,
			input:  "ignored",
			want:   "42",
		},
		{
			name:    "nil result is an error",
			script:  `d:filter "F" { |in| }`,
			input:   "abc",
			wantErr: "filter returned no value",
		},
		{
			name:    "error raised in proc propagates",
			script:  `d:filter "F" { |in| error "boom" }`,
			input:   "abc",
			wantErr: "boom",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			plugins, inst := newTestPlugins()
			if _, err := inst.EvalString(ctx, tt.script); err != nil {
				t.Fatal(err)
			}
			proc, ok := plugins.filters["plugin:f"]
			if !ok {
				t.Fatalf("filter not registered")
			}

			res, err := proc.Filter(ctx, tt.input)
			if tt.wantErr != "" {
				if err == nil || !strings.Contains(err.Error(), tt.wantErr) {
					t.Fatalf("expected error containing %q, got %v (res %+v)", tt.wantErr, err, res)
				}
				return
			}
			if err != nil {
				t.Fatal(err)
			}
			if res.Output != tt.want {
				t.Errorf("output = %q, want %q", res.Output, tt.want)
			}
		})
	}
}

func TestPluginFilters_FilterBuiltinValidation(t *testing.T) {
	ctx := context.Background()

	tests := []struct {
		name   string
		script string
	}{
		{name: "missing proc", script: `d:filter "Label"`},
		{name: "no args", script: `d:filter`},
		{name: "empty label", script: `d:filter "  " { |in| $in }`},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			plugins, inst := newTestPlugins()
			if _, err := inst.EvalString(ctx, tt.script); err == nil {
				t.Fatal("expected an error")
			}
			if len(plugins.filters) != 0 {
				t.Errorf("no filter should be registered, got %v", plugins.filters)
			}
		})
	}
}

func TestSlugify(t *testing.T) {
	tests := []struct {
		in   string
		want string
	}{
		{"String: To Upper Case", "string-to-upper-case"},
		{"  Lines: Go Template…  ", "lines-go-template"},
		{"already-a-slug", "already-a-slug"},
		{"MiXeD CaSe 123", "mixed-case-123"},
		{"---", ""},
	}
	for _, tt := range tests {
		if got := slugify(tt.in); got != tt.want {
			t.Errorf("slugify(%q) = %q, want %q", tt.in, got, tt.want)
		}
	}
}

func TestApp_PluginIntegration(t *testing.T) {
	ctx := context.Background()
	app := NewApp(nil)
	dir := t.TempDir()
	writePluginFile(t, dir, "upper.ucl", `d:filter "String: To Upper Case" { |in| strs:to-upper $in }`)
	writePluginFile(t, dir, "rev.ucl", `d:filter "Custom: Echo" { |in| $in }`)

	app.plugins.LoadDir(ctx, app.uclInst, dir)

	t.Run("ListProcessors shadows built-in by label", func(t *testing.T) {
		resp := app.ListProcessors()

		byLabel := map[string][]string{}
		for _, r := range resp {
			byLabel[r.Label] = append(byLabel[r.Label], r.Name)
		}
		if names := byLabel["String: To Upper Case"]; len(names) != 1 || names[0] != "plugin:string-to-upper-case" {
			t.Errorf("expected only the plugin entry for the shadowed label, got %v", names)
		}
		if names := byLabel["Custom: Echo"]; len(names) != 1 || names[0] != "plugin:custom-echo" {
			t.Errorf("expected plugin entry, got %v", names)
		}
		if names := byLabel["String: To Lower Case"]; len(names) != 1 || names[0] != "lower-case" {
			t.Errorf("built-in should be unaffected, got %v", names)
		}
		for i := 1; i < len(resp); i++ {
			if resp[i-1].Label > resp[i].Label {
				t.Errorf("response not sorted by label at %d: %q > %q", i, resp[i-1].Label, resp[i].Label)
			}
		}
	})

	t.Run("lookupProcessor prefers plugin then falls back to built-in", func(t *testing.T) {
		if proc, ok := app.lookupProcessor("plugin:custom-echo"); !ok || proc.Label != "Custom: Echo" {
			t.Errorf("plugin lookup failed: %v %v", proc, ok)
		}
		if proc, ok := app.lookupProcessor("lower-case"); !ok || proc.Label != "String: To Lower Case" {
			t.Errorf("built-in lookup failed: %v %v", proc, ok)
		}
		if _, ok := app.lookupProcessor("nope"); ok {
			t.Error("unknown key should not be found")
		}
	})
}